AstroLab
Why does iron change a star’s fate?
Fusion, collapse and neutron captures
A star’s mass determines its burning stages; near iron and nickel, fusion ceases to be a sustained energy source.
Why explore it?
Read “Where do our atoms come from?”; distinguish protons, neutrons, isotopes and fusion. A simplified account of reactions and sites: not every collapse explodes, and contributions to elements depend on models.